I just looked at the calendar for 2022 between April 10th and September 24th
I found plenty of room for 16 county championship fixtures spread across 18 fixture weeks running Monday to Thursday
I also found plenty of slots early season for some white ball cricket at the weekend, perhaps primarily played on Friday's or Sunday's with a few counties opting to play Saturday's. I can't for the life of me see any reason why the counties couldn't play alternate red and white ball cricket throughout most of the season so there is an even balance of both formats throughout. Then you'd not get completely blank July and August like we're experiencing now.
Even with 18 county championship focused weeks there is still room in the schedule for 6 weeks of rest / other formats.
These 6 weeks of rest could be used to prioritise some white ball cricket - May 1st to 8th counties could play 3 50 over matches, then June 5th to 18th I scoped out a 2 week solid block for the T20's where counties could play 5 or 6 matches and a spare week at either the start or the end of August where they could fit in play off's or semi finals or whatever. The rest of June and July should be county championship Mon-Thurs then T20's on Friday's and Sunday's.
And with all the room I've found in the schedule for the three formats I haven't even had to start April 3rd nor had to go on to early October either. You hear a lot about how tricky it is for the fixture schedulers but if they get the players to accept switching red to white ball cricket early, middle and late season rather than having these obscene 5 or 6 week blocks of one single format then it becomes far simpler.
It is certainly NOT an impossibly short window of time when you consider they now start early April and drag it out to early October.